The Blind Spot of the Bryan Johnson Era: Mental Illness and Physical Fitness in 4 Research Papers

Let me start with the conclusion. It has been reported that elderly people with depression are more prone to frailty (a state of physical and mental decline due to aging) than those without depression. The difference was particularly significant in men. On the other hand, a meta-analysis of multiple studies has reported that even in people with depression or schizophrenia, exercise improved cardiorespiratory fitness (the ability to take in and use oxygen). It is not the case that “if you have a mental illness, you have to give up on physical fitness.”

A question often overlooked in the anti-aging boom

Bryan Johnson, a US entrepreneur known for his efforts to slow aging, has led many to become interested in whether aging can be reversed.

I should clarify beforehand: these four papers do not examine Mr. Johnson himself or his methods. This article addresses a question that is close to his topic but rarely discussed.

Those two questions are as follows:

Does having a mental illness make physical aging (frailty or decline in physical fitness) more likely to progress?
How much cardiorespiratory fitness can be regained through exercise?

When talking about aging, people tend to focus on supplements and the latest tests. However, the relationship between mental state and physical fitness is a familiar issue for many people and their families.

Why it is reliable: 4 compiled research papers

All four of these papers are meta-analyses. A meta-analysis is a method of collecting multiple studies on the same topic and summarizing the results statistically. Its strength is that it is less susceptible to chance than a single study.

Study A (Chu et al., 2019): Summarized 14 studies including 84,351 people aged 65 and over to examine the relationship between depression and frailty.
Study B (Vancampfort et al., 2017): Examined the cardiorespiratory fitness of people with severe mental illnesses such as schizophrenia, bipolar disorder, and depression from 23 studies.
Study C (Stubbs et al., 2016): Summarized 7 randomized controlled trials (trials where participants are randomly assigned to an exercise group or a non-exercise group) in which people with depression were asked to exercise.
Study D (Vancampfort et al., 2015): Examined whether exercise improves cardiorespiratory fitness in people with schizophrenia.

A and B address “how the body is likely to be affected by mental illness.” C and D address “how much it can change through exercise.” Combining these two makes it easier to answer the questions at hand.

Finding 1: Elderly people with depression are more prone to frailty

The conclusion of Study A is clear: elderly people with depression are more prone to frailty than those without.

The focus is on the gender difference. The indicator for comparing the likelihood (odds ratio; the higher it is above 1, the more likely it is to occur) was 4.76 for men and 2.25 for women. The difference was particularly large in men with depression.

Discovery 2: Exercise Improves Cardiorespiratory Fitness

In Study C, when people with depression exercised, their cardiorespiratory fitness clearly improved. The effect size (Hedges’ g; the larger the number, the clearer the difference) was 0.64.

In Study D, cardiorespiratory fitness also improved in people with schizophrenia. The value was 0.40, and it was 0.43 in the 4 studies compared to the control group.

In both cases, the direction of the “improvement” is the same. However, there was a difference in the magnitude of the improvement. We will look at what this difference means in detail in the paid section.

What you will learn in the paid section

How to read the numbers from the 4 papers in detail, and the line between “what can be said and what cannot”
The reason for the difference in effect size between depression and schizophrenia, and how to interpret discrepancies between studies
Steps to start exercising in real life, things you should not do, and guidelines for medical consultation and advice

Reading in detail 1: Depression and Frailty (Study A)

Study A searched 5 medical databases for papers published between January 2000 and December 2016. The subjects were community-dwelling elderly people aged 65 and over. The total number of people was 84,351, and there were 14 studies.

The interesting thing about this study is that it carefully checked the “conditions under which the results did not fluctuate.” Study design (whether it was a cross-sectional or longitudinal study), region, method of determining depression, method of determining frailty, and whether other factors were adjusted. No matter how the conditions were divided, there was no meaningful difference in the results.

In other words, it does not seem to be a result that was “just by chance in this region” or “just because of this measurement method.”

However, the only difference was gender. It was 4.76 for men and 2.25 for women. Calculating by dividing 4.76 by 2.25, the value for men is about 2.1 times that of women. This gender difference was also statistically significant (p=.002).

Why is the difference larger in men? The abstract does not investigate the reason. It is safe to accept only the point that “special attention is needed for depression in men” without filling in the gaps with speculation. The authors also state that special attention should be paid to elderly men with depression.

Reading in detail 2: Severe Mental Illness and Cardiorespiratory Fitness (Study B)

Study B examined the cardiorespiratory fitness of people with severe mental illnesses such as schizophrenia, bipolar disorder, and depression. The average of the 23 studies combined was 28.7 mL/kg/min (95% confidence interval 27.3–30.0).

This unit is “the amount of oxygen that can be taken in per 1 kg of body weight per minute.” The larger the number, the higher the endurance. Please consider the 95% confidence interval as “the range in which the true value is likely to fall.”

There is a point to note. Within the scope of the abstract available for this article, it is not possible to read specific numerical values compared to healthy people. Therefore, I cannot write “what percentage lower it is than healthy people.”

Even so, the authors’ conclusion is clear. They state that the treatment of severe mental illness should include a focus on improving physical fitness. This is because cardiorespiratory fitness is an important indicator related to heart and vascular disease and premature death. They also state that professionals who support an active lifestyle should be added to psychiatric treatment teams.

Reading in detail 3: Exercise Trial for Depression (Study C)

Study C collected only randomized controlled trials. Seven trials included eight aerobic exercise programs (exercises that raise the heart rate slightly, such as walking or running).

There were 293 people in the exercise group and 205 in the comparison group, totaling 498 people. The average age of the exercise group was 40.3 years, with an age range reported from 27.2 to 64.7 years. The proportion of women varied significantly by study, ranging from 35% to 100%.

The subjects were not limited to those diagnosed with depression; they also included people with depressive symptoms exceeding diagnostic thresholds.

The results show that exercise clearly improved cardiorespiratory fitness (g=0.64, 95% confidence interval 0.32–0.96). The lower bound of the confidence interval is also far from 0, making the conclusion that it “improved” relatively robust. The authors state that this is a clinically meaningful improvement.

Reading in detail (4): Exercise research for schizophrenia (Study D)

Study D searched for research up to May 2015.

First, an analysis summarizing 7 studies (77 people) showed that exercise improved cardiorespiratory fitness (g=0.40, 95% confidence interval 0.16–0.64, p=0.001).

Next, data from 4 studies comparing against a control group were examined. There were 53 people in the exercise group and 48 in the comparison group, totaling 101 people. Here too, the cardiorespiratory fitness of the exercise group clearly improved (g=0.43, 95% confidence interval 0.05–0.82, p=0.028).

However, the lower bound of the confidence interval is 0.05. It is honest to read this as being quite close to 0, meaning there is still a range in the magnitude of the effect. The small number of participants may be one factor.

Discrepancies between studies and their reasons

Lining up the four papers reveals several “discrepancies.”

Discrepancy 1: Magnitude of effect. Study C on depression was 0.64, while Study D on schizophrenia was 0.40 and 0.43. Calculating by dividing 0.64 by 0.43, there is a difference of about 1.5 times. However, one cannot conclude from this that “exercise is more effective for depression.” The number of participants differs significantly, with 498 in Study C and 101 in the comparative studies of Study D. The age of the subjects and the content of the exercise also differ. The confidence intervals also overlap. It is reasonable to accept that “both show improvement, but the difference in magnitude is unclear.”

Discrepancy 2: Age. Study A focuses on those 65 and older. On the other hand, the average age of those who exercised in Study C was 40.3 years. In other words, none of these four papers directly confirmed that “elderly people with depression who exercise can prevent frailty.” “Elderly depression is related to frailty” and “people with depression can improve cardiorespiratory fitness through exercise” are two separate facts, and connecting them is the task of future research.

Discrepancy 3: Schizophrenia and frailty. Study A deals only with depression. The relationship between schizophrenia and frailty is not directly examined in these four papers. Study B examines cardiorespiratory fitness, but not frailty itself.

Discrepancy 4: Direction of causality. Study A includes research that examined only a single point in time. Therefore, it cannot be definitively stated from these results whether “depression leads to frailty,” “frailty leads to depression,” or both.

The perspective of “physical fitness” over “body weight”

There is a message common to Studies C and D. It is the idea of looking not only at “fatness” but also at “fitness.” Study B also calls for attention to be paid to improving physical fitness.

Study C states that setting goals for physical fitness can be one of the easier methods to implement. Study D also suggests that attention should be paid to both improving physical fitness and reducing body weight.

Even if you don’t lose weight immediately, you may find yourself less short of breath or that climbing stairs becomes easier. These changes also have value.

Steps for Daily Life

The following is a guide on how to start, based on the four studies. Since specific times and frequencies are not mentioned in the research summaries, I have intentionally omitted them. Please first consult with your primary care physician to decide.

Consult your primary care physician.Tell them you want to exercise and ask about any precautions regarding your current treatment or physical condition.
Know your current physical fitness.Make a note of your current state, such as whether you get out of breath on stairs or how far you can walk.
Start small.The exercise used in Study C was aerobic. Start with light exercise that makes you breathe a little harder, such as a walk.
Create a system to keep going.Study B states that support from professionals is important. It is easier to continue if you work with hospital rehabilitation staff, exercise specialists, family, or friends.
Record changes other than weight.Focus on changes in physical fitness, such as shortness of breath, reduced fatigue, and walking distance.

For family members, please be especially mindful of changes in elderly men, such as a lack of energy or reduced outings. Study A recommends aiming to reduce frailty by detecting depression early.

Things to Avoid

Stopping treatment on your own judgment and replacing it with exercise.This study examined changes in cardiopulmonary function and did not show that exercise can replace medical treatment.
Suddenly doing intense exercise.The more your physical fitness has declined, the more likely this is to cause injury or worsen your condition.
Judging success solely by weight.Even if your weight does not change, your physical fitness may be improving.
Blaming the person or forcing them to exercise.When someone is feeling down, exercise is not easy. Celebrating the days they were able to do it together will help them continue.
Copying a celebrity’s method exactly.The trendy rejuvenation method may not necessarily suit your medical condition or body.

Guidelines for Consultation

Please consult a medical institution as soon as possible in the following cases:

You have persistent feelings of depression or a lack of interest in anything, which is interfering with your work or housework.
You have persistent difficulty sleeping or eating.
You feel a decline in your body, such as sudden weight loss, walking more slowly, or becoming easily fatigued.
You experience chest pain, severe shortness of breath, or dizziness during exercise (please stop exercising immediately and consult a doctor).

If you have feelings of wanting to die or wanting to disappear, do not hesitate to contact a medical institution, local consultation service, or emergency services immediately.

Summary

It has been reported that people aged 65 and over with depression are more prone to frailty. The difference was particularly significant in men (odds ratio: 4.76 for men, 2.25 for women).
This relationship remained largely consistent even when changing regions or measurement methods. However, the direction of causality cannot be definitively stated.
It has been reported that exercise improves cardiorespiratory fitness in both people with depression (g=0.64) and people with schizophrenia (g=0.40, 0.43 in control comparisons).
Whether exercise can prevent frailty in elderly people with depression is not directly verified by these four papers.
A realistic first step is to focus not just on weight, but on ‘physical fitness,’ and to start small while consulting with your primary care physician.

When you want to change the aging process, mental health and physical fitness should be considered as a set. These four studies provide numerical clues to help you think about that.

References

Chu W et al., “The Relationship Between Depression and Frailty in Community-Dwelling Older People: A Systematic Review and Meta-Analysis of 84,351 Older Adults.” Journal of Nursing Scholarship, 2019 (PMID 31328878)
Vancampfort D et al., “Cardiorespiratory Fitness in Severe Mental Illness: A Systematic Review and Meta-analysis.” Sports Medicine, 2017 (PMID 27299747)
Stubbs B et al., “Exercise improves cardiorespiratory fitness in people with depression: A meta-analysis of randomized control trials.” Journal of Affective Disorders, 2016 (PMID 26523669)
Vancampfort D et al., “Exercise improves cardiorespiratory fitness in people with schizophrenia: A systematic review and meta-analysis.” Schizophrenia Research, 2015 (PMID 26475214)

*This article is an introduction to research and is not medical advice. Please be sure to consult with a medical professional, such as your primary care physician, regarding symptoms, treatment, and how to start exercising. The figures in the article are based on the abstracts of each paper and do not guarantee that the same results will occur for individuals.

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